A wide variety of lock arrangements have been used for securing bars to a frame in a fixed position to support and retain lading carried by the frame during transport. These bars, commonly known as dunnage bars, are releasably secured at each end in the fixed position by locking devices that typically permit each bar to be completely disengaged from the frame and removed to unload the cargo.
In one such commercially successful dunnage bar locking arrangement heretofore marketed by applicant, the lock includes a saddle having a base and parallel sidewalls spaced from each other by a distance to receive and laterally capture an end of the dunnage bar. A latch is mounted on an end wall of the saddle at a position spaced from the saddle base, and is rotatable on the end wall about an axis parallel to the saddle base between a lower position at which the latch captures the dunnage bar end against the saddle base between the sidewalls, and an upper position that permits removal of the dunnage bar end. A coil spring urges the latch against the saddle end wall and cooperates with a detent integral with an end wall for preventing rotation of the latch from the lower position to the upper position unless the latch is manually biased against the spring force. A cam surface on the detent automatically moves the latch against the spring force as the latch is manually pivoted from the upper to the lower bar-locking position.
Another such dunnage bar lock arrangement of applicant is that described in U.S. Pat. No. 5,037,256, which discloses a bar of rectangular cross section having a lateral opening in one side of the bar adjacent to the end of the bar, and a saddle that has a base and parallel sidewalls spaced from each other to receive the bar end on the saddle base between the sidewalls. Positioned beneath the saddle base is an L-shaped latch which has a leg that extends upwardly from the saddle base adjacent to the sidewalls, and a finger overlying and spaced .from the saddle base by a distance corresponding to the cross sectional dimension of the bar end. The latch is pivotally mounted to the saddle beneath the saddle base, and a coil spring is captured between the saddle and latch bases for urging the latch finger to the position overlying the saddle base. The bar end engages a camming surface on the latch finger for pivoting the latch with respect to the saddle against the force of the spring so that the bar end is received within the saddle, with a locating pin on the saddle base received within the opening at the bar end. In this position, the bar end is thus locked beneath the latch finger and between the saddle sidewalls.
Although both of applicant's prior art lock arrangements described above have enjoyed substantial commercial acceptance and success, improvements nonetheless remain desirable. For example, before loading or unloading freight, these prior art locks must be completely disengaged and the bar removed from the frame, possibly resulting in expensive loss or theft of the detached bar and associated locking hardware. It is therefore a general object of the present invention to provide a dunnage bar locking arrangement that prevents the bar from being completely detached from the frame, even during cargo loading and unloading, thereby virtually eliminating loss or theft of the bar and locking hardware. It is also an object of the present invention to provide a locking arrangement that keeps the bar captive to the frame while enabling the bar to be moved relative to the frame between a releasably latched position for securing freight for shipment, and a position displaced from the latched position that provides sufficient clearance between the bar and the freight for loading or unloading freight. Another object of the present invention is to provide a bar lock arrangement in which the bar may be latched or unlatched without requiring operator manipulation of the locking device itself. Yet another object of the invention is to provide a lock arrangement that may be used with dunnage bars of the same or similar construction as those utilized with applicant's prior art locking arrangements, reducing the cost of changeover from either of applicant's existing lock arrangements to that of the present invention. A further object of the invention is to provide a bar lock arrangement that is less expensive to manufacture than are similar prior art locks, including both of applicant's prior art arrangements.